I would induce emesis. A pecan is just the right size to obstruct such a small dog's small intestine. The dose of 3% hydrogen peroxide is 5 ml (one measuring teaspoon) per 5 lbs of body weight given with a small poultry baster placed between Riley's cheek teeth and cheek. Riley should vomit within 15 minutes of dosing. If not, please repeat the same dose. Keep me posted, please.